1. Technical Field
The present invention relates to a cooling apparatus for memory modules, more particularly, to a cooling apparatus for a Fully Buffered Dual In-lined Memory Module (FBDIMM).
2. Discussion of Related Art
A memory module having a plurality of chips mounted on a printed circuit board (PCB) may be classified as a single in-line memory module (SIMM) or a dual in-line memory module (DIMM). A SIMM is a memory module having memory chips mounted on a single side of a PCB and a DIMM is a memory module having memory chips mounted on both sides of the PCB. FBDIMMs are DIMMs which operate in accordance with a packet protocol, which usually operate at higher-speed and at higher capacity than non FBDIMMs.
The FBDIMM includes a plurality of memory chips and an advanced memory buffer (AMB) which handles received packets at high data rate and converts the packets into memory commands. The AMB interfaces with memory chips mounted on the DIMM and transfers data to and from the plurality of memory chips. Due to the high speed operation and large volume of data transfer, a large amount of heat is generated. The AMB is usually the chip that generates the most heat and thus operates at a higher temperature among all chips onboard the FBDIMM. It is not unusual to find the heat generated by the AMB being an order of magnitude higher than that of the memory circuit chips of the FBDIMM.
Conventionally, one or more heat sink or heat spreading device can be coupled to the AMB to spread the heat generated there-from. FIG. 10 shows a single heat spreader 310 coupled to the AMB 220. The heat spreader 310 dissipates heat from the AMB 220 but heat generated from the circuit chips 230 are not dissipated with any heat spreading medium other than the natural airflow. FIG. 11 shows a conventional monolithic heat spreading device 410 which is placed on the AMB 220 and on circuit chips 230 of the same line. In such configuration, with the AMB and the circuit chips operating at different temperatures, the heat spreader 410 may not dissipate heat effectively because the heat spreader 410 may act as a heat conduit to raise instead of lower the temperature at the circuit chips disposed adjacent to the AMB 220. Further, dissipation of heat at the hottest operating chip may be difficult when adjacent chips are also generating heat, aggregating instead of spreading heat generated from all the chips.
A need therefore exists for a monolithic cooling apparatus having a plurality of heat spreaders and having varying heat-dissipating characteristics to correspond to the different amount of heat generated from different chips on the package.
A need also exists for a cooling apparatus having multiple heat spreading portions, with a high heat spreading portion thermally coupled to an AMB and lesser heat spreading portions thermally coupled to memory modules of an FBDIMM.